Motor controller for an industrial truck



April 1957 B. I. ULINSKI MOTOR CONTROLLER FOR AN INDUSTRIAL TRUCK 3Sheets-Sheet 1 Original Filed April 10, 1961 INVENTOR. 5. [/L/NSK/ BYavug'ai A Trap/v5 y April 18, 1967 B. l. ULlNSKl MOTOR CONTROLLER FOR ANINDUSTRIAL TRUCK 5 Sheets-Sheet 2 Original Filed April 10, 1961 5.ULHYSKI I April 18, 1967 B. I. ULINSKI 3,315,058

MOTOR CONTROLLER FOR AN INDUSTRIAL TRUCK Original Filed April 10, 1961 3Sheets-Sheet 5 g Y r N d INVENTOR.

( L/NSK/ BY km??? United States Patent 8 Claims. (Cl. 200-153) Thisapplication is a division of my application Ser. No. 436,989, which wasfiled Feb. 12, 1965, as a continuation of my application Ser. No.101,705, filed Apr. 10, 1961, now abandoned.

This invention relates to an electrically operated industrial truck, andin particular to a controller for the electric traction motor of thetruck.

Various control systems have heretofore been proposed and used whichincorporate various types of controllers or switch devices for varyingthe speed of the motor by varying the resistance or the arrangement ofthe field windings in the motor circuit. Each of these systems, however,has required rather elaborate, complicated wiring systems whichnecessarily added to the cost of fabrication and maintenance of thetruck, as well as special consideration of the design of the mechanicalcomponents of the truck, in order to accommodate and protect the wiringsystem.

The purpose of this invention is to provide a controller for thetraction motor of an industrial truck which is mechanically extremelysimple and requires only a very simple wiring system thereby eliminatingthe fabrication and maintenance problems inherent in the use of priorcontrol systems.

In accordance with the invention, the speed of the traction motor iscontrolled by connecting separate field windings for the motor into themotor circuit in various combinations by means of a controller which ismounted 'directly on the outer surface of the traction motor and isconnected with the field windings through openings provided in the motorhousing. A suitable linkage system is provided connecting the controllerwith manually operable means, such as a foot treadle or hand lever,positioned adjacent the operators compartment so that the controller maybe easily actuated by the operator of the truck to vary the speed of themotor. By this arrangement. the wiring of the control system is greatlysimplified thereby facilitating fabrication and maintenance of thetruck. Furthermore, as the wiring of the control system is enclosedwithin the motor housing and the controller housing, it is wellprotected.

As a feature of the invention, there is provided a very simple,relatively inexpensive, extremely compact controller which isparticularly adapted for use on an industrial truck because it occupiesrelatively little space and may be readily secured directly to the motorhousing. Furthermore, the controller is so designed as to maintaincontinuity of the motor circuit during connection and disconnection ofthe field windings, so that electrical arcing is minimized and smootheroperation is obtained then would be the case if the motor circuit werecompletely broken each time a field winding were connected ordisconnected.

The invention and its advantages having been broadly described, a moredetailed description of one embodiment of the invention is givenhereafter by reference to the accompanying drawings wherein:

FIG. 1 is a side elevational view of an industrial truck with partsbroken away to show the incorporation of the controller of the inventionin the truck.

FIG. 2 is a section view taken on line 22 of FIG. 1 to show theconnection of the field windings of the traction motor with thecontroller.

FIG. 3 is a sectional view of a controller constructed in accordancewith the invention.

FIG. 4 is a sectional view taken on the line 44 of FIG. 3 and showingthe controller secured to the side of the housing of the electrictraction motor.

FIG. 5 is a perspective View showing one pair of contact fingers and theactuating mechanism for the fingers;

FIG. 6 is a diagrammatic showing of the controller and traction motorcircuit with the contact fingers of the controller positioned to connectfour field windings of the motor in series to give a first motor speed;

FIG. 7 is a diagrammatic showing similar to that of FIG. 4 but showingthe contact fingers positioned to short out one field winding coil whileconnecting the other three field windings in series to give a highermotor speed; and

FIG. 8 is a diagrammatic showing similar to that of FIGURE 5 but showingthe contact fingers positioned to short out two field windings and toconnect two field windings in parallel to give a still higher motorspeed.

Referring to the drawings and in particular to FIG. 1, the controller ofthe invention is shown incorporated in an industrial truck 1 having anelectrical traction motor 2 for driving front wheels 3, and having acompartment 4 for housing batteries for supplying electrical energy tothe motor 2. As best shown in FIG. 2, the traction motor has fourseparate field windings 2a, 2b, 2c and 2d, which surround an armature2e.

In accordance with the invention, the speed of the motor is varied byconnecting the field windings into the motor circuit in variouscombinations by means of a controller 5 which is secured directly to theouter surface of the housing 2 of the motor 2 and is connected to thefield windings through openings in the housing 2 The controller 5 isadapted to be actuated to vary the speed of the motor 2 by means of afoot treadle 6 which is pivotally mounted on the floor 7 of theoperators compartment of the truck and is connected to the controller 5by means of a link 8 which is pivotally secured at one end to anoperating lever 9 of the controller 5, and pivotally secured to theother end to an extension 6a and a lug 11 secured to the floor 7 servesto urge the treadle 6 and controller 5 to neutral position.

It can be seen by this arrangement for controlling the speed of themotor 2, only a very simple wiring system is required therebysimplifying fabrication and maintenance of the truck while at the sametime insuring that the wiring system'is well protected.

Referring to FIGS. 3 and 4, the controller 5 includes a main housingconveniently formed in three parts, including a base 12 formed ofsuitable rigid insulating material, a hollow rectangular frame 13 whichseats in a peripheral groove 14 in the base 12 and forms the four sidesof the housing, and a cover plate 15. The resulting housing is securedto the outer surface of the housing 2f of the motor 2 by means of fourcorner studs 16 which have threaded inner ends 16a which extend throughthe base 12 and thread into the motor housing 2f to clamp the base 12 tothe motor housing. The studs 16 also have outer threaded ends 16b whichextend through the corners of the cover plate 15 and receive nuts 17 forholding the cover plate 15 and the frame 13 assembled on the base 12.

Four pairs of spaced terminal posts 18, 19, 20 and 21 having each aflange 23 intermediate its ends, as best shown in FIG. 4, extend intothe controller housing through holes 22 provided in the base 12, andextend in the opposite direction through bushings 25 formed of suitableinsulating material which line openings 26 provided through the motorhousing 2 When the controller is secured to the motor housing 2 by meansof the studs 16, the flanges 23 of the terminal posts 18, 19, 20 and 21seat in counterbores 24 formed in the ends of the holes 22, and theflanges 23 are clamped between the base 12 and the outer surface of thebushings 25 so that the terminal posts are retained in proper position.As diagrammatically shown in FIG. 6, each of the field windings 2a, 2b,2c and 2d of the electric motor 2 is connected between the terminals ofone pair of the four pairs of ter minal posts 18, 19, 20 and 21. As bestshown in FIGS. 2 and 4, the ends of the field windings are convenientlyconnected to the inner ends of the terminal posts which extend throughthe bushings 25.

Each of the terminal posts of the pairs of terminal posts 18, 19 and 20is provided with a pivotally mounted contact finger 28 which includes ahub portion 28a which is rotatably mounted on the terminal posts withinthe frame 13.

The contact finger 28 mounted on each of the terminal posts 18, 19 and20 on the right-hand side of the controller, as viewed in FIG. 3,extends between the next adjacent pair of terminal posts immediatelyabove so that it can pivot between a position of physical contact withthe hub portion 28a of the contact fingers 28, or Contact blocks 29 inthe case of terminal posts 21, mounted on either the left-hand orright-hand terminal post of the next adjacent pair of terminal posts toform an electrical circuit between the terminal posts. Thus, the contactfinger 28 mounted on the right-hand terminal post 18 extends between thepair of terminal posts 19 and may be moved into physical contact withthe hub portion 28a of the contact finger 28 mounted on either thelefthand or right-hand terminal post 19. The contact finger 28 mountedon the right-hand terminal post of the pair of terminal posts 19 extendsbetween terminal posts 20 and may be moved into physical contact withthe hub portion 28a of the contact finger 28 mounted on either theleft-hand or right-hand terminal post 20. Similarly, the contact finger28 mounted on the right-hand terminal post 20 extends between the pairof terminal posts 21 and may be moved into physical contact with thecontact block 29 mounted on either the left-hand or right-hand terminalpost 21.

Each of the contact fingers 28 mounted on the lefthand terminal postextends to the left of the left-hand terminal post of the next adjacentpair of terminal posts immediately above, as viewed in FIG. 3, and canbe moved into or out of physical contact only with the hub portion 28aof the contact fingers 28 or the contact block 29 mounted on theleft-hand terminal posts of the next adjacent pair of terminal posts.

The outer surfaces 28b of the hub portion 28a and the outer surfaces 29aof the contact blocks 29 are preferably convexed so that the fingers 28make substantially uniform line contact therewith regardless of thepivotal position of the hub portions 28a or fingers 28. The contactblocks 29 are conveniently clamped in position on the terminal posts 21by nuts 30 threaded on the outer ends of the terminal posts 21.

The contact fingers 28 mounted on the right-hand terminal posts 18, 19and 20 are urged to the left toward the left-hand terminal posts of thenext succeeding pairs of terminal posts, by means of coil springs 31,while the contact fingers 28 mounted on the left-hand terminal posts 18,19 and 20 are urged to the right toward the same left-hand terminalposts by coil springs 32. As best seen in FIGS. 4 and 5, the inner endsof the springs 31 and 32 extend through slots 33 provided in the outerends of the upper and lower terminal posts 18, 19 and 20 and the outerends of the springs 31 and 32 are hooked around pins 34 which extendfrom the edge of each of the fingers 28 so as to urge the fingers 28toward the left-hand terminal posts. The springs 31 and 32, as well asthe fingers 28, are retained on their respective terminal posts 18, 19or 20 by suitable split retaining clips 35 which seat in 4 groovesprovided in the ends of the terminal posts, as can best be seen in FIG.4.

The fingers 28 mounted on the left and right-hand ter minal posts ofeach of the pairs of terminal posts 18, 19 and 20 are adapted to bemoved away from the left-hand terminal posts against the force of thesprings 31 or 32 associated therewith by means of an actuating rod 36formed of suitable insulating material. As best shown in FIG. 5, theactuating rods 36 extend through elongated slots 28c provided in each ofthe contact fingers 28 of each pair of terminal posts, and each rod 36has an enlarged portion 36a which is positioned between the left andright-hand fingers 28. Thus, if the actuating rod 36 is moved to theleft, the contact finger 28 mounted on the left-hand terminal post isengaged by the enlarged portion 36a and is moved out of electricalcontact with the left-hand terminal post of the next adjacent pair ofterminal posts. If the actuating rod 36 is moved to the right, theenlarged portion 36a thereof engages the finger 28 mounted on theright-hand terminal post and moves the finger out of electrical contactwith the left-hand terminal post of the next adjacent pair of terminalposts into electrical contact with the right-hand terminal post. It willbe noted that the actuating rods 36 can move only the right-hand contactfinger 28 or the left-hand contact finger away from the left-handterminal post at one time so that one finger 28 is always in contactwith each of the left-hand terminal posts to maintain a circuit throughthe controller at all times.

The left-hand end of each of the actuating rods 36 engages in a seat 37formed in the end surface of a hollow plunger 38 which is slidablyreceived in a hollow spring seat 39. Each of the spring seats 39* has athreaded end 39a which is threaded through the wall of the frame 13 tosecure the seat 39 to the controller. A compression spring 40 isdisposed in each of the spring seats 39 with the right-hand end of thespring 40 hearing against the inner surface of the plunger 38 and theleft-hand end of the spring 40 hearing against the inner bottom surfaceof the spring seat 39 so as to urge the plunger 38 and the actuating rod36 associated therewith to the right. The strength of the spring 40 ismade greater than that of the spring 31 so that the springs 40 actingthrough the plunger 38 and actuating rods 36 can move the controlfingers 28 of the right-hand terminal posts away from the left-handterminal posts against the force of the springs 31.

The positions of the control rods 36 and, therefore, the positions ofthe contact fingers 28 are controlled by cams 41 of a predeterminedcontour which are secured to a rotatably mounted shaft 42. Each of theearns 41 engages a cam follower in the form of a ball 43 which in turnengages the top of one of the rods 36. As the earns 41 are rotated, therods 36 are either moved to the left against the force of the springs 40by the earns 41, or moved to the right by the springs 40, to vary thepositions of the contact fingers 28.

The right-hand ends of the rods 36 and the balls 43 are guided insuitable guide sleeves 44 which extend between the frame 13 and the wallof a housing 4 5 which encloses the earns 41. The housing 45 is securedto the frame 13 by means of bolts 46 which extend through the housing 45and thread into the frame 13. The shaft 42 is supported for rotation inbearings 47 which are provided at each end of the housing 45 and areheld in position by means of through bolts 48. The shaft 42 is adaptedto be rotated by means of the lever 9 which is secured to one endthereof and, as previously described, is connected to the foot treadle 6by link 8, whereby movement of the foot treadle rotates the shaft 42 andthe cams 41 to change the positions of the contact fingers 28.

The lower end of the frame 13 (FIG. 3) is provided with a terminal 50which extends through a suitable insulating grommet 51 and is connectedby means of a flexible connector 52 to the hub portion 28a of the contact finger 28 mounted on the left-hand terminal post 18- by a screw 53,and the upper end of frame 13 is provided with a terminal 54 whichextends through an insulating grommet 55 and is connected to theright-hand terminal posts 21 by a connector 56. The terminals 50' and 54and the two connections 52 and 56 are all that are required to connectthe controller in the motor circuit.

As previously stated, each of the separate field windings 2a, 2b, 2c and2d of the motor 2 is connected between the terminals of one of the pairsof terminals 18, 19, 20 and 21, and the speed of the motor is controlledby changing the positions of the contact fingers 28 to vary the numberof the field windings which are connected in the motor circuit, and themanner in which they are connected in the circuit. The peripheralcontours of the cams 41 are so selected that as the cams 41 are rotated,the contact fingers 28 will be moved to vary the number and manner ofconnection of the field windings in the motor circuit in such a sequencethat the speed of the motor will be increased step by step as the camsare rotated in one direction.

This varying of the speed of the motor by movement of the contactfingers to vary the number and combination in which the field windingsof the motor are connected in the motor circuit is best illustrated inthe diagrams of FIGS. 6, 7 and 8. In these diagrams, the four separatefield windings 2a, 2b, 2c and 2d of the D.C. motor 2 are shown connectedrespectively between the terminals of each pair of the terminal posts18, 19, 20 and 21. The lower end side of the controller is shownconnected through the terminal 50 to a lead 57 from a source of D.C.electrical energy, such as the battery 58, and the upper end of thecontroller is shown connected through the terminal 54 to a lead 59 toone side of the armature 2e of the D.C. motor. A lead 60 connects theother side of the armature 2e to the battery 58. Contacts 61a, 61b, 61cand 61d represent the contacts of a conventional starting and reversingswitch. In the diagrams, the contacts 6 1a and 61d are shown closed tocomplete a circuit in one direction through the armature 2e.

FIG. 6 illustrates a first speed position of the contact fingers 28 inwhich the fingers 28 mounted on the righthand terminal posts 18, 19 and20 are in electrical contact with the left-hand terminal posts 19, 20and 21, and the fingers 28 mounted on the left-hand terminal posts havebeen moved out of electrical contact with the lefthand terminal posts19, 20 and 21 by the enlarged portions 36a of the actuating rods 36through movement of the rods 36 to the left by the cams 41. In thisposition of the fingers 28, the field windings 2a, 2b, 2c and 2d areconnected in series with the armature 2e to provide low speed operationof the motor.

In FIG. 7, there is shown a second speed position in which the finger 28mounted on the left-hand post 18 has been moved by its spring 32 to theright into electrical contact with the left-hand terminal post 19 due torelease of lower actuating rod 36 by its cam 41 to allow sufficientmovement thereof to the right by its spring pressed plunger 38 torelease the finger 28 for such movement. This movement of the loweractuating rod 36 is insufficient to move the finger 28 on the right-handpost 18 out of electrical contact with the left-hand terminal 19, sothat this finger remains in the same position as in FIG. 6. The othercontact fingers 28 also remain in the same position as in FIG. 6. Themovement of the one finger 28 shorts out the field winding 2a whilefield windings 2b, 2c and 2d remain connected in series so as toincrease the speed of the motor.

A third higher speed position (not shown in the drawings) may beobtained by moving the contact finger 28 mounted on the left-handterminal post 19 into electrical contact with the left-hand terminalpost 20 so as to short out field winding 2b' in addition to fieldwinding 2a, so as to leave only field windings 2c and 2d connected inseries in the circuit. A fourth higher speed may be obtained by movingcontact finger 28 mounted on the lefthand terminal post 20 intoelectrical contact with the lefthand terminal post 21 to short out fieldwinding 20 in addition to field windings 2b and 2a so as to leave onlyfield windings 2d in the circuit.

A fifth speed may be obtained by movement of the contact fingers to theposition shown in FIG. 8 in which all the left fingers 28 are inelectrical contact with the left hand terminal posts 19, 20 and 21,while uppermost rod 36 has moved uppermost contact finger 28 on theright-hand terminal post 20 into electrical contact with the right-handterminal post 21. Field windings 2a and and 2b are now shorted out, andfield windings 2c and 2d are connected in parallel. The positions of thefingers 28, as shown in FIG. 8, are the same as that shown in FIG. 3.

A sixth higher speed may be obtained by moving the contact finger 28mounted on the right-hand terminal post 19 from the position ofelectrical contact with the lefthand terminal post 20 as shown in FIG. 8to a position of electrical contact with the right-hand terminal post 20whereby field windings 2b, 2c and 2a are connected in parallel, andfield winding 2a is shorted out. A seventh higher speed may be obtainedby also moving the contact finger 28 mounted on the right-hand terminalpost 18 from the position as shown in FIG. 6 to a position of electricalcontact with the right-hand terminal post 19 so that all the fieldwindings 2a, 2b, 2c and 2d are connected in parallel.

Thus, through the control of rods 36 and the operating portions 360, itis possible to position the spring pressed fingers 28 into varyingcombinations so as to connect the fields into various electricalcombinations to obtain a great number of motor speeds.

As previously stated, the peripheral contours of the earns 41 areselected and related so as to give the proper sequence of positions ofthe contact fingers 28 to provide a gradual step-by-step increase in thespeed of the motor as the shaft 42 is rotated in one direction, and togive a gradual step-by-stepdecrease in the motor as the shaft 42 isrotated in the opposite direction to return it to its original position.

It will be noted thta due to the location of the enlargements 36a of theactuating rods 36 between the pairs of contact fingers 28 at least onecontact finger 28 of each pair of terminals is at all times inelectrical contact with one of the next adjacent pairs of terminals, asthe field windings are connected and disconnected, so that thecontinuity of the motor circuit is maintained with resulting decrease inelectrical arcing and smoother operation than would be the case if themotor circuit were broken each time that a field winding was connectedor disconnected.

It will also be noted that the controller requires very few differentparts. Thus, each of the contact fingers 28, the terminal posts 18, 19and 20, springs 31 and 32, actuating rods 26, balls 43, guides 44,plungers 37, spring seats 39 and springs 40 are identical therebydecreasing the number of different necessary parts and the cost of thecontroller, as well as simplifying the construction of the controller.

From the preceding description, it can be seen that there is provided animproved control system and controller for the 'traction motor of anindustrial truck which eliminates the complicated wiring arrangement ofsystems heretofore used so as to simplify the fabrication andmaintenance of the truck. While a preferred form of the invention hasbeen shown and described, it will be appreciated that changes andmodifications may be made thereon without departing from the spirit andscope of the invention.

I now claim:

1. A controller comprising, at least two pairs of spaced terminals, acontact finger pivotally mounted on each terminal of one pair ofterminals, one contact finger being pivotally movable into and out ofelectrical contact with one terminal of the other pair of terminals, theother contact finger being pivotally movable between positions ofelectrical contact with both terminals of the other pair of terminals,and means for selectively pivoting said fingers to three differentpositions of electrical contact with said terminals of said other pairof terminals including a first position in which both said contactfingers are in electrical contact with said one terminal of the otherpair of terminals, a second position in which said one contact finger isout of electrical contact with said one terminal of the other pair ofterminals and said other contact finger is in electrical contact withsaid one terminal of said other pair of terminals, and a third positionin which said one contact finger is in electrical contact with said oneterminal of said other pair of terminals and said other contact fingeris in electrical contact with said other terminal of said other pair ofterminals, whereby elements connected between each of said pair ofterminals may be connected in parallel, in series, or certain elementsshorted out.

2. A controller as set forth in claim 1, and including means urging bothof said contact fingers toward said first position of said fingers, andmanually operated means coacting with said contact fingers for placingsaid fingers in their second and third positions.

3. A controller as set forth in claim 1, and including spring meanspressing both of said contact fingers to said first position of saidfingers, means coacting with each finger for moving the finger againstits spring pressure, and manually operated cam means controlling saidcoacting means so as to place said contact fingers in their second andthird positions.

4. A controller comprising, a series of pairs of spaced terminals, acontact finger pivotally mounted on each terminal of each pair ofterminals except for an end pair of terminals of the series, one contactfinger of each pair of terminals being pivotally movable into and out ofa position of electrical contact with one terminal of the next adjacentpair of terminals, and means for pivoting said pair of terminals beingpivotally movable between positions of electrical contact with bothterminals of the next adjacent pair of terminals, and means for pivotingsaid fingers of each pair of terminals through a sequence of differentpositions of electrical contact with said next adjacent pair ofterminals, including a position in which both said contact fingers areboth in contact with one terminal of said next adjacent pair ofterminals, a position in which said one contact finger is out of contactwith said one terminal of said next adjacent pair of terminals and saidother finger is in contact with said one terminal of said next adjacentpair of terminals and a position in which said one contact finger ofsaid one pair of terminals is in contact with said one terminal of saidnext adjacent pair of terminals and said other contact finger is incontact with said other terminal of said next adjacent pair ofterminals, whereby to first connect elements connected between each ofsaid pair of terminals all in series, then progressively short out allbut one element and finally progressively connect all the elements inparallel.

5. A controller comprising a first housing, a plurality of spacedterminals operably mounted in said housing, contact fingers rotatablymounted on said spaced terminals, said contact fingers movable between afirst and second position, actuating means for moving said contactfingers between said first and second positions, first means for movingsaid actuating means in a first direction for moving said contactfingers into said first position, a second housing associated with thefirst housing, second means enclosed in said second housing and opposingsaid first means for moving said actuating means in a second directionwhereby said actuating means imparts a force to said contact fingers formovement into said second position.

6. In a controller of the character described in claim 5 wherein saidactuating means comprises a plurality of rod members which extendthrough said contact fingers, an enlarged portion on each of saidcontrol rods for engaging said contact fingers whereupon movement ofsaid control rods will actuate said contact fingers.

7. In a controller of the character described in claim 5 wherein saidfirst means for moving said actuating means comprises a biasing springmounted in said first housing and in axial alignment with said actuatingmeans.

8. In a controller of the character described in claim 5 wherein saidsecond means comprises a cam shaft having a plurality of cams mountedthereon, linkage means attached to said cam shaft for imparting rotarymotion thereto, follower means intermediate said cams and said actuatingmeans whereby rotary movement of said cam shaft imparts linear motion tosaid actuating means thereby overcoming said first means and therebymoving said control fingers into said second position.

References Cited by the Examiner UNITED STATES PATENTS 2,579,135 12/1951Alexander 200-l53

1. A CONTROLLER COMPRISING, AT LEAST TWO PAIRS OF SPACED TERMINALS, ACONTACT FINGER PIVOTALLY MOUNTED ON EACH TERMINAL OF ONE PAIR OFTERMINAL, ONE CONTACT FINGER BEING PIVOTALLY MOVABLE INTO AND OUT OFELECTRICAL CONTACT WITH ONE TERMINAL OF THE OTHER PAIR OF TERMINALS, THEOTHER CONTACT FINGER BEING PIVOTALLY MOVABLE BETWEEN POSITIONS OFELECTRICAL CONTACT WITH BOTH TERMINALS OF THE OTHER PAIR OF TERMINALS,AND MEANS FOR SELECTIVELY PIVOTING SAID FINGERS TO THREE DIFFERENTPOSITIONS OF ELECTRICAL CONTACT WITH SAID TERMINALS OF SAID OTHER PAIROF TERMINALS INCLUDING A FIRST POSITION IN WHICH BOTH SAID CONTACTFINGERS ARE IN ELECTRICAL CONTACT WITH SAID ONE TERMINAL OF THE OTHERPAIR OF TERMINALS, A SECOND POSITION IN WHICH SAID ONE CONTACT FINGER